Auto-Calibration%20and%20Control%20Applied%20to%20Electro-Hydraulic%20Valves - PowerPoint PPT Presentation

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Auto-Calibration%20and%20Control%20Applied%20to%20Electro-Hydraulic%20Valves

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Title: Auto-Calibration%20and%20Control%20Applied%20to%20Electro-Hydraulic%20Valves


1
Auto-Calibration and Control Applied to
Electro-Hydraulic Valves
  • A Ph.D. Thesis Proposal
  • Presented to the Faculty of the
  • George Woodruff School of Mechanical Engineering
  • at the Georgia Institute of Technology
  • By
  • PATRICK OPDENBOSCH
  • Committee Members
  • Nader Sadegh (Co-Chair, ME)
  • Wayne Book (Co-Chair, ME)
  • Chris Paredis (ME)
  • Bonnie Heck (ECE)
  • Roger Yang (HUSCO Intl.)

2
PRESENTATION OUTLINE
  • INTRODUCTION
  • PROBLEM STATEMENT
  • OBJECTIVES
  • REVIEW OF MOST RELEVANT WORK
  • PROPOSED RESEARCH
  • PRELIMINARY WORK
  • EXPECTED CONTRIBUTIONS
  • CONCLUSION

3
INTRODUCTION
  • CURRENT APPROACH
  • Electronic control
  • Use of solenoid Valves
  • Energy efficient operation
  • New electrohydraulic valves
  • Conventional hydraulic spool valves are being
    replaced by assemblies of 4 independent valves
    for metering control

Low Pressure
High Pressure
Spool Valve
Spool piece
Spool motion
Piston
Piston motion
4
INTRODUCTION
  • CURRENT APPROACH
  • Electronic control
  • Use of solenoid Valves
  • Energy efficient operation
  • New electrohydraulic valves
  • Conventional hydraulic spool valves are being
    replaced by assemblies of 4 independent valves
    for metering control

Valve motion
Low Pressure
High Pressure
Piston motion
5
INTRODUCTION
  • ADVANTAGES
  • Independent control
  • More degrees of freedom
  • More efficient operation
  • Simple circuit
  • Ease in maintenance
  • Distributed system
  • No need to customize

Valve motion
Low Pressure
High Pressure
Piston motion
6
INTRODUCTION
  • METERING MODES
  • Standard Extend
  • Standard Retract
  • High Side Regeneration
  • Low Side Regeneration
  • DISADVANTAGES
  • Nonlinear system
  • Complex control

Valve motion
Low Pressure
High Pressure
Piston motion
7
INTRODUCTION
Coil Cap
Adjustment Screw
  • POPPET ADVANTAGES
  • Excellent sealing
  • Less faulting
  • High resistance to contamination
  • High flow to poppet displacement ratios
  • Low cost and low maintenance

Modulating Spring
Input Current
Coil
Armature
Pilot Pin
Control Chamber
Armature Bias Spring
U.S. Patents (6,328,275) (6,745,992)
Pressure Compensating Spring
Main Poppet
Forward (Side) Flow
Reverse (Nose) Flow
8
INTRODUCTION
Coil Cap
Adjustment Screw
  • Electro-Hydraulic Poppet Valve (EHPV)
  • Poppet type valve
  • Pilot driven
  • Solenoid activated
  • Internal pressure compensation
  • Virtually zero leakage
  • Bidirectional
  • Low hysteresis
  • Low gain initial metering
  • PWM current input

Modulating Spring
Input Current
Coil
Armature
Pilot Pin
Control Chamber
Armature Bias Spring
U.S. Patents (6,328,275) (6,745,992)
Pressure Compensating Spring
Main Poppet
Forward (Side) Flow
Reverse (Nose) Flow
9
INTRODUCTION
  • VALVE CHARACTERIZATION
  • Flow Conductance Kv
  • or

10
INTRODUCTION
  • FORWARD MAPPING
  • REVERSE MAPPING

Side to nose
Forward Kv at different input currents A
Nose to side
Reverse Kv at different input currents A
11
INTRODUCTION
  • MOTIVATION
  • Need to control valves KV
  • Currently done by inversion of the steady-state
    input/output characteristics
  • Requires individual offline calibration
  • CHALLENGES
  • Online learning of steady state and transient
    characteristics
  • Online estimation of individual Kv.
  • ADVANTAGES
  • No individual offline calibration
  • Design need not be perfect and sufficiently
    fast
  • Maintenance scheduling can be implemented from
    monitoring and detecting the deviations from the
    normal pattern of behavior.

12
PRESENTATION OUTLINE
  • INTRODUCTION
  • PROBLEM STATEMENT
  • OBJECTIVES
  • REVIEW OF MOST RELEVANT WORK
  • PROPOSED RESEARCH
  • PRELIMINARY WORK
  • EXPECTED CONTRIBUTIONS
  • CONCLUSION

13
PROBLEM STATEMENT
  • PURPOSE
  • Develop a general theoretical framework for
    auto-calibration and control of general nonlinear
    systems. It is intended to explore the
    feasibility of the online learning of the
    systems characteristics while improving its
    transient and steady state performance without
    requiring much a priori knowledge of such system.
  • APPLICATION
  • This framework is applied to a hydraulic system
    composed of electro-hydraulic valves in an effort
    to study the applicability of having a
    self-calibrated system.

14
PROBLEM STATEMENT
  • RESEARCH QUESTIONS
  • How well can the systems mappings be learned
    online while at the same time trying to achieve
    good state tracking performance?
  • How can the tracking error dynamics be maintained
    stable while applying learning and estimation on
    the system?
  • How is the learning affected by input saturation
    and time-varying dynamics?
  • In particular for the EHPVs, how well can the
    forward and reverse flow mappings be learned?
  • How can the learned mappings be used for fault
    detection?

15
PRESENTATION OUTLINE
  • INTRODUCTION
  • PROBLEM STATEMENT
  • OBJECTIVES
  • REVIEW OF MOST RELEVANT WORK
  • PROPOSED RESEARCH
  • PRELIMINARY WORK
  • EXPECTED CONTRIBUTIONS
  • CONCLUSION

16
OBJECTIVES
  • THEORETICAL
  • Development of a general formulation for control
    of nonlinear systems with parametric uncertainty
    and time-varying characteristics
  • Development of a formulation for auto-calibration
    of nonlinear systems
  • Study of learning dynamics online along with
    fault diagnosis
  • Improve Kv control of EHPVs
  • EXPERIMENTAL
  • Analysis and validation on the effectiveness of
    the proposed method
  • Study of the accuracy of the auto-calibration and
    possible drift problems
  • Development of computationally efficient
    algorithms
  • Development of a nonlinear observer for state
    estimation for unmeasurable states

17
PRESENTATION OUTLINE
  • INTRODUCTION
  • PROBLEM STATEMENT
  • OBJECTIVES
  • REVIEW OF MOST RELEVANT WORK
  • PROPOSED RESEARCH
  • PRELIMINARY WORK
  • EXPECTED CONTRIBUTIONS
  • CONCLUSION

18
RELEVANT WORK REVIEW
  • CONTROL
  • Sadegh, N., (1995), A nodal link perceptron
    network with applications to control of a
    nonholonomic system, IEEE Transactions on Neural
    Network, Vol. 6, No. 6, pp. 1516-1523.
  • Sadegh, N., (1998), A multilayer nodal link
    perceptron network with least squares training
    algorithm, International Journal of Control, Vol.
    70, No. 3, pp. 385-404.

19
RELEVANT WORK REVIEW
Sadegh (1995)
  • The plant is linearized about a desired
    trajectory
  • A Nodal Link Perceptron Network (NLPN) is
    employed in the feedforward loop and trained with
    feedback state error
  • The control scheme needs the plant Jacobian and
    controllability matrices obtained offline
  • Approximations of the Jacobian and
    controllability matrices can be used without
    loosing closed loop stability.

20
RELEVANT WORK REVIEW
Sadegh (1998)
  • Nodal Link Perceptron Network (NLPN)
  • Functional approximation is achieved by the
    scaling of basis functions
  • The class of basis functions are to be selected
    as well as their weights are to be trained so
    that the functional approximation error is within
    prescribed bounds

21
RELEVANT WORK REVIEW
  • FLOW OBSERVER
  • O'hara, D.E., (1990), Smart valve, in Proc
    Winter Annual Meeting of the American Society of
    Mechanical Engineers pp. 95-99
  • Book, R., (1998), "Programmable electrohydraulic
    valve", Ph.D. dissertation, Agricultural
    Engineering, University of Illinois at
    Urbana-Champaign
  • Garimella, P. and Yao, B., (2002), Nonlinear
    adaptive robust observer for velocity estimation
    of hydraulic cylinders using pressure measurement
    only, in Proc ASME International Mechanical
    Engineering Congress and Exposition pp. 907-916

22
RELEVANT WORK REVIEW
  • O'hara (1990), Book (1998)
  • Concept of Inferred Flow Feedback
  • Requires a priori knowledge of the flow
    characteristics of the valve via offline
    calibration

Squematic Diagram for Programmable Valve
23
RELEVANT WORK REVIEW
  • Garimella and Yao (2002)
  • Velocity observer based on cylinder cap and rod
    side pressures
  • Adaptive robust techniques
  • Parametric uncertainty for bulk modulus, load
    mass, friction, and load force
  • Nonlinear model based
  • Discontinuous projection mapping
  • Adaptation is used when PE conditions are
    satisfied

24
RELEVANT WORK REVIEW
  • Liu and Yao (2005)
  • Modeling of valves flow mapping
  • Online approach without removal from overall
    system
  • Combination of model based approach,
    identification, and NN approximation
  • Comparison among automated modeling, offline
    calibration, and manufacturers calibration

25
RELEVANT WORK REVIEW
  • HEALTH MONITORING
  • Polycarpou and Vemuri (1995)
  • Selmic and Lewis (2000)
  • Linear modeling techniques
  • NN for nonlinear identification

Failure Detection and Accommodation Monitoring
off-nominal behavior
Multimodel Failure Detection
26
RELEVANT WORK REVIEW
  • HEALTH MONITORING
  • Polycarpou, M.M. and Vemuri, A.T., (1995),
    Learning methodology for failure detection and
    accommodation, IEEE Control Systems, Vol. No.
    pp. 16-24.
  • Selmic, R.R. and Lewis, F.L., (2000),
    Identification of nonlinear systems using rbf
    neural networks Application to multimodel
    failure detection, in Proc XVI International
    Conference on "Material flow, machines, and
    devices in industry"

27
PRESENTATION OUTLINE
  • INTRODUCTION
  • PROBLEM STATEMENT
  • OBJECTIVES
  • REVIEW OF MOST RELEVANT WORK
  • PROPOSED RESEARCH
  • PRELIMINARY WORK
  • EXPECTED CONTRIBUTIONS
  • CONCLUSION

28
PROPOSED RESEARCH
  • AUTO-CALIBRATION AND CONTROL
  • k 0,1,2 (discrete-time index)
  • 0 ui iUMAX, i 1,2,,m
  • Set of admissible states
  • Set of admissible inputs

29
PROPOSED RESEARCH
  • AUTO-CALIBRATION AND CONTROL
  • k 0,1,2 (discrete-time index)
  • 0 ui iUMAX, i 1,2,,m
  • The control purpose is to learn the input
    sequence uk that forces the states of the
    system xk to follow a desired state trajectory
    dxk as k?8
  • PROPOSED Adaptive approach without requiring
    detailed knowledge about the systems model

30
PROPOSED RESEARCH
  • SQUARE NONLINEAR SYSTEM
  • ASSUMPTIONS
  • The system is strongly controllable
  • The system is strongly observable
  • The functions F and H are continuously
    differentiable

31
PROPOSED RESEARCH
  • SQUARE NONLINEAR SYSTEM
  • DEFINITIONS
  • Jacobian Matrix
  • Controllability Matrix
  • Observability Matrix

32
PROPOSED RESEARCH
  • SQUARE NONLINEAR SYSTEM
  • CONTROL DESIGN
  • Tracking Error
  • Error Dynamics

33
PROPOSED RESEARCH
  • SQUARE NONLINEAR SYSTEM
  • CONTROL DESIGN
  • Error Dynamics
  • Deadbeat Control Law

34
PROPOSED RESEARCH
  • SQUARE NONLINEAR SYSTEM
  • CONTROL DESIGN
  • Deadbeat Control Law
  • Proposed Control Law

35
PROPOSED RESEARCH
  • Proposed Control Law

Nominal inverse mapping
Estimation of Jacobian and controllability
Feedback correction
inverse mapping correction
36
PROPOSED RESEARCH
Nominal inverse mapping
Inverse Mapping Correction
uk
xk
NLPN
PLANT
dxk
Adaptive Proportional Feedback
Jacobian Controllability Estimation
37
PROPOSED RESEARCH
  • ESTIMATION APPROACHES
  • Modified Broyden

38
PROPOSED RESEARCH
  • ESTIMATION APPROACHES
  • Recursive Least Squares

39
PROPOSED RESEARCH
  • APPLICATION
  • Kv Observer

For each valve
40
PROPOSED RESEARCH
  • APPLICATION
  • Health Monitoring
  • Failures sensor fault, wear of the mating parts,
    contamination, break of a component, or component
    stiction
  • Assess valves behavior with respect to the
    nominal behavior.
  • Establish the criteria to declare faulting on the
    valves by studying the deviations from the
    nominal pattern.

Kv as a Function of Input Current Deviations
from Nominal Patterns
41
PROPOSED RESEARCH
  • THEORETICAL TASKS
  • Work on the convergence properties of the
    estimated matrices
  • Perform analysis about the closed loop stability
    of the overall system.
  • Work on a nonlinear observer for the valves flow
    conductances.
  • EXPERIMENTAL TASKS
  • Hydraulic testbed setup
  • Sensor integration, calibration, and filtering
    design
  • Data acquisition and analysis
  • Validation of theory
  • Compare the performance under learning to that of
    fixed input/output mapping

42
PRESENTATION OUTLINE
  • INTRODUCTION
  • PROBLEM STATEMENT
  • OBJECTIVES
  • REVIEW OF MOST RELEVANT WORK
  • PROPOSED RESEARCH
  • PRELIMINARY WORK
  • EXPECTED CONTRIBUTIONS
  • CONCLUSION

43
PRELIMINARY WORK
Implemented Nominal Mapping
  • NONLINEAR 1ST ORDER DISCRETE TIME SYSTEM

Comparison implemented and true steady state
mapping
44
PRELIMINARY WORK
45
PRELIMINARY WORK
Closed-loop and open-loop performance
46
PRELIMINARY WORK
Estimated Jacobian and Controllability
47
PRELIMINARY WORK
  • MORE INFORMATION AT
  • Opdenbosch, P. and Sadegh, N., (2005), Control of
    discrete-time systems via online learning and
    estimation, in Proc IEEE/ASME International
    Conference on Advanced Intelligent Mechatronics
    pp. 975-980

48
PRELIMINARY WORK
  • Single EHPV learning control being investigated
    at Georgia Tech
  • Controller employs Neural Network in the
    feedforward loop with adaptive proportional
    feedback
  • Satisfactory results for single EHPV used for
    pressure control

49
PRELIMINARY WORK
50
PRELIMINARY WORK
  • Initial test response, no NLPN learning

Flow Conductance
Estimated Jacobian and Controllability
51
PRELIMINARY WORK
  • EHPV response with NLPN learning

Flow Conductance
Estimated Jacobian and Controllability
52
PRELIMINARY WORK
  • MORE INFORMATION AT
  • Opdenbosch, P. and Sadegh, N., (2005), Control of
    electro-hydraulic poppet valves via online
    learning and estimation, in Proc ASME
    International Mechanical Engineering Congress and
    Exposition, IMECE (Accepted)

53
PRESENTATION OUTLINE
  • INTRODUCTION
  • PROBLEM STATEMENT
  • OBJECTIVES
  • REVIEW OF MOST RELEVANT WORK
  • PROPOSED RESEARCH
  • PRELIMINARY WORK
  • EXPECTED CONTRIBUTIONS
  • CONCLUSION

54
EXPECTED CONTRIBUTIONS
  • An alternative methodology for control system
    design of nonlinear systems with time-varying
    characteristics and parametric uncertainty.
  • A method to estimate and learn the flow
    conductance of the valve online.
  • Guidelines to experimentally use this control
    methodology and health monitoring efficiently in
    the area of electro-hydraulic control.

55
PRESENTATION OUTLINE
  • INTRODUCTION
  • PROBLEM STATEMENT
  • OBJECTIVES
  • REVIEW OF MOST RELEVANT WORK
  • PROPOSED RESEARCH
  • PRELIMINARY WORK
  • EXPECTED CONTRIBUTIONS
  • CONCLUSION

56
CONCLUSIONS
  • The proposed control methodology combines
    adaptive proportional feedback control with
    online corrected feedforward compensation
  • The input/output mapping of the system can be
    easily extracted via a functional approximator on
    the feedforward compensation
  • Extensive knowledge about the dynamics of the
    system are not needed a priori for satisfactory
    performance
  • The proposed method is to be employed in a
    Wheatstone bridge arrangement of novel
    Electro-Hydraulic Poppet Valves seeking a
    self-calibrated system
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